1. Field of the Invention
The instant invention relates generally to fine particulate filtration near building foundations and, specifically, to an adhesive-bearing filter fabric adapted to fit, and permanently adhere, to a plank shaped form that is installed in a generally moist or wet environment. The plank shaped form that comprises a cofeature of this invention is disclosed in U.S. Pat. Nos. 5,120,162 and 5,224,799, hereinafter incorporated by reference.
2. Discussion of Relevant Art
The previously incorporated references, U.S. Pat. Nos. 5,120,162 and 5,224,799 relate to a permanently installed, plank shaped form-drain and accessories therefor which bear foramens on specific surfaces thereof and which, in subterranean emplacement, serve as both a concrete form and a footing/foundation drain. Neither of these patents disclose, nor deal with, apparatus that would prevent the passage of fine particulate, as slurry or silt, into the drainage network that is realized by the normal installation of the patented form-drain. Recognition of the requirement for sump pumps reasonably highlights the need for filtration before the particulate-laden drainage enters the drain system and gravity-flows to the sump(s).
Art dealing with drain-contacting filtration apparatus includes U.S. Pat. Nos. 4,720,209, 3,946,762 and 4,704,048. The first, '209, discloses a filter-covered foraminous (perforate, slotted, or multi-holed) drain pipe that is used to drain a drywell structure. The fabric material is applied over the pipe as a rectangular wrap that is secured about the pipe by joining it to its margins by an undisclosed "suitable" adhesive. The second patent, '762, discloses a filter fabric formed into a sleeve by joining opposing longitudinal margins using stitching, to form a seam. The sleeve is then drawn over all the foraminous tubular pipes of a drainage system. Finally, the third patent, '048, teaches a plank-like, insulator-drain having a filter fabric secured thereto. The insulator-drain is applied on the exterior basement walls of a structure and is essentially solid rather than hollow. Vertical grooves in the isulative plank are designed to accept tubular retainers that secure the fabric in the grooves and to the plank surface.
The aforementioned filtration apparatus patents, having significant deficiencies, cannot satisfy our requirements for providing fine particulate and silt exclusion from the herein identified form-drain apparatus. Because of the conventional gravel and fill requirements demanded of the form-drain installation, adhesion of the filter fabric to the from-drain is mandatory. Further, the adhesion must be permanent, so fixation of the fabric to the plastic of the form drain must be made in contemplation of dissimilarity in materials, i.e., plastic, siliceous, etc. The apparatus and methodology of '209 is found wanting because first, there is no ground or fill surround that can conceivably move the fabric from its emplacement, regardless of freeze-thaw or earth movement conditions. Such is not the case with the '162 form-drain. Second, the fabric of '209 is further secured by a clamping ring that serves to immobilize the pipe; thus, it has no need for rigorous adhesive treatment. Finally, the securing of the fabric to itself begs the question of "suitability" of adhesive since, like seaming of the seeve of '762, the margins may be stitched and yet function as the patentee devised.
Turning to the sleeve of '762, we determined that, although the sleeve fabric will exclude some measure of coarse particulate, such is more likely enhanced by the fact that the patented apparatus is an irrigation system and water flows out of the conduits rather than into them. Thus, the fabrics disclosed do not face the conditions of particulate and slurry contamination to which our invention is exposed. A greater deficiency of the '762 sleeve is the fact that were it to be adapted to the form-drain apparatus disclosed as in 1. Field of the Invention, the requisite fabric (relative to thickness, strength and mesh) would be unwieldy and excessive. From a consideration of labor and cost factors alone, use of the '762 filtration is not advisable.
Lastly, filter fabric adherence, as taught in '048, would be contraindicated with the form-drain. The latter is devised with minimum surface distortion (save the foramens of a single side) and the grooving of the former teaches contrary to the use of adhesives.
Thus, we invented a filter device that would successfully exclude fine particulates from the fluids flowing into the instant form-drain. This was accomplished by adapting suitable filter fabrics to fit onto the form-drain after it has been installed in the field. To secure the fabic properly, it has been provided a (longitudinal) margin adhesive that is covered by a removable, nontacky paper or plastic strip. To better understand the types of materials used, we refer the reader to the hereinafter disclosed products and current practices.